The present invention generally relates to a double overhead cam (referred to as "DOHC", hereinbelow) type engine having a spark plug provided in a hollow between a pair of head covers and more particularly, to a head cover arrangement for the DOHC engine, in which a lid is provided between the head covers so as to prevent penetration of rain water, dust, etc. into a plug hole for the spark plug.
Conventionally, in DOHC type engines, it has been generally so arranged that a pair of cam shafts are provided at an upper portion of a cylinder head so as to be disposed at opposite positions relative to a longitudinal centerline of the engine and head covers are, respectively, provided above the cam shafts. In the known cylinder head of the above described arrangement, a groove is formed between the opposite head covers and a spark plug is provided in the groove so as to be fitted into a plug hole of the cylinder head. In order to prevent penetration of rain water, dust, etc. into the groove, a cover is, for example, provided at an upper portion of the groove as disclosed by Japanese Patent Laid-Open Publication No. 143128/1983.
However, the known cylinder head of the above described arrangement has such an inconvenience that since a high-tension cord connected to the spark plug is passed through a bore of the above described cover provided at the upper portion of the groove so as to be drawn upwardly from the cover, penetration of rain water, etc. into the plug hole may readily take place if sealing of the bore becomes loose.
Furthermore, in order to mount the cover in the known cylinder head, it is necessary to connect the high-tension cord to the spark plug after the high-tension cord has been passed through the bore of the cover and then, mount the cover in position. Thus, the known cylinder head has such a drawback that assembly and disassembly of the cover cannot be performed efficiently.